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• 1. [Article] White-breasted nuthatch density and nesting ecology in oak woodlands of the Willamette Valley, Oregon

  Habitat loss causes a reduction in available resources for wildlife, alters the configuration of remaining habitat, and may isolate wildlife populations. White-breasted nuthatches (Sitta carolinensis) ...

  Citation × Citation Citation Abstract Copy Title: White-breasted nuthatch density and nesting ecology in oak woodlands of the Willamette Valley, Oregon Author: Viste-Sparkman, Karen Habitat loss causes a reduction in available resources for wildlife, alters the configuration of remaining habitat, and may isolate wildlife populations. White-breasted nuthatches (Sitta carolinensis) are experiencing long-term population declines in the Willamette Valley of Oregon, where they are historically associated with oak woodlands. As secondary cavity-nesters, white-breasted nuthatches may be limited by the availability of existing cavities for nesting and roosting. Oak vegetation in the Willamette Valley has changed since European-American settlement times from vast areas of open oak savanna to isolated closed-canopy stands separated by agricultural fields. We examined nuthatch density, nest cavity selection, and nest success in relation to oak woodland structure and landscape context. We conducted point transect surveys in 3 strata: woodland interiors, large woodland edges, and small woodlands. We located and monitored nuthatch nests and sampled vegetation at nest locations and matching random locations around each nest. Woodland structure and edge density were measured at a 178-m radius (home range) scale, and landscape context was measured using vegetation cover within a 1-km radius around point transects and nests. We used program DISTANCE to fit detection functions and calculate nuthatch densities. We used conditional logistic regression to compare nest locations with random locations, and analyzed nest success with Mayfield logistic regression. White-breasted nuthatch density was significantly higher in small woodlands than in edges of large woodlands, which had higher nuthatch density than woodland interiors. Density of nuthatches increased with a combination of oak cover within a 1-km radius of the point, edge density within a 178-m radius, and number of oak trees >50 cm diameter at breast height (dbh) within a 100-m radius. Nest cavities were situated in oak trees containing more cavities than random oak trees that had cavities, and oak trees used as nest trees had a larger dbh than oak trees within random plots. Local woodland structure at nest locations was characterized by larger trees, measured by greater mean dbh, canopy cover, and basal area of oaks than random locations within the home range. Nest success in natural cavities was 71% and was not predicted by attributes of nest cavities, nest trees, local woodland structure at nests, woodland structure at the home range scale, or landscape context. These results suggest that the most suitable habitat for white-breasted nuthatches in the Willamette Valley includes oak woodlands in close proximity to one another with a high proportion of edge and mature oak trees. Managers should preserve trees containing cavities and large oak trees whenever possible. Thinning of small oaks and removal of conifers in oak woodlands to create more open, savanna-like conditions may also promote the development of larger oaks with more spreading branches, providing more opportunities for cavities to form and more foraging surface area for nuthatches. Title: White-breasted nuthatch density and nesting ecology in oak woodlands of the Willamette Valley, Oregon Author: Viste-Sparkman, Karen Habitat loss causes a reduction in available resources for wildlife, alters the configuration of remaining habitat, and may isolate wildlife populations. White-breasted nuthatches (Sitta carolinensis) are experiencing long-term population declines in the Willamette Valley of Oregon, where they are historically associated with oak woodlands. As secondary cavity-nesters, white-breasted nuthatches may be limited by the availability of existing cavities for nesting and roosting. Oak vegetation in the Willamette Valley has changed since European-American settlement times from vast areas of open oak savanna to isolated closed-canopy stands separated by agricultural fields. We examined nuthatch density, nest cavity selection, and nest success in relation to oak woodland structure and landscape context. We conducted point transect surveys in 3 strata: woodland interiors, large woodland edges, and small woodlands. We located and monitored nuthatch nests and sampled vegetation at nest locations and matching random locations around each nest. Woodland structure and edge density were measured at a 178-m radius (home range) scale, and landscape context was measured using vegetation cover within a 1-km radius around point transects and nests. We used program DISTANCE to fit detection functions and calculate nuthatch densities. We used conditional logistic regression to compare nest locations with random locations, and analyzed nest success with Mayfield logistic regression. White-breasted nuthatch density was significantly higher in small woodlands than in edges of large woodlands, which had higher nuthatch density than woodland interiors. Density of nuthatches increased with a combination of oak cover within a 1-km radius of the point, edge density within a 178-m radius, and number of oak trees >50 cm diameter at breast height (dbh) within a 100-m radius. Nest cavities were situated in oak trees containing more cavities than random oak trees that had cavities, and oak trees used as nest trees had a larger dbh than oak trees within random plots. Local woodland structure at nest locations was characterized by larger trees, measured by greater mean dbh, canopy cover, and basal area of oaks than random locations within the home range. Nest success in natural cavities was 71% and was not predicted by attributes of nest cavities, nest trees, local woodland structure at nests, woodland structure at the home range scale, or landscape context. These results suggest that the most suitable habitat for white-breasted nuthatches in the Willamette Valley includes oak woodlands in close proximity to one another with a high proportion of edge and mature oak trees. Managers should preserve trees containing cavities and large oak trees whenever possible. Thinning of small oaks and removal of conifers in oak woodlands to create more open, savanna-like conditions may also promote the development of larger oaks with more spreading branches, providing more opportunities for cavities to form and more foraging surface area for nuthatches. Close

• 2. [Article] Butterfly and flower community composition among prairie-oak ecosystem habitats in the Willamette Valley, Oregon

  Prairie-oak ecosystems in the Willamette Valley, Oregon have experienced habitat loss and degradation; most of these ecosystems are fragmented into smaller patches. Prairie-oak butterfly species, in the ...

  Citation × Citation Citation Abstract Copy Title: Butterfly and flower community composition among prairie-oak ecosystem habitats in the Willamette Valley, Oregon Author: Powers, Breanna F. Prairie-oak ecosystems in the Willamette Valley, Oregon have experienced habitat loss and degradation; most of these ecosystems are fragmented into smaller patches. Prairie-oak butterfly species, in the Willamette Valley, have decreased dramatically due to loss or degradation of habitat. More research is needed on sustaining the populations of butterflies in prairie-oak ecosystems. The purpose of my study was to examine the role prairie-oak habitats have in structuring butterfly communities in the Willamette Valley. My objectives were to: (1) assess how butterfly community structure and species composition (density, abundance, and species richness) varies along an oak canopy cover gradient in order to understand the role of habitat type in structuring butterfly communities in prairie-oak ecosystems; (2) characterize community composition of nectar resources and environmental variables known to be important for butterfly species. I also investigated temporal and structural relationships between butterfly and flower communities. I found that butterfly abundance and density were greater (p < 0.02) in prairies than in oak savannas or oak woodlands; however, species richness did not differ among habitats (p = 0.54). Ordination of prairie-oak habitats in butterfly species space with a joint plot overlay of environmental variables revealed several strong correlations; butterfly community structure was negatively correlated with litter and oak canopy cover and positively correlated to vegetation cover. The prairie, oak savanna, and oak woodland habitat types differed in nectar species community structure, though this difference was small. Non-native species were some of the most abundant flowers species found in all stands. Butterfly communities were positively related to flower communities. I detected significant seasonal patterns among the habitat types in butterfly and flower communities. Prairies appear to be the most important habitat for native butterfly populations compared to oak savanna and oak woodlands. Flowers were most prevalent in prairies and prairies had the highest percentage of native flower species; the prevalence of non-native flower species was greatest in oak woodlands. My study may represent a short-term community transition as a result of management or it may represent a more permanent community. Further study is needed to understand the effects of different management strategies for habitat restoration and the presence of non-native flower species on butterflies in prairie-oak ecosystems in the Willamette Valley. Title: Butterfly and flower community composition among prairie-oak ecosystem habitats in the Willamette Valley, Oregon Author: Powers, Breanna F. Prairie-oak ecosystems in the Willamette Valley, Oregon have experienced habitat loss and degradation; most of these ecosystems are fragmented into smaller patches. Prairie-oak butterfly species, in the Willamette Valley, have decreased dramatically due to loss or degradation of habitat. More research is needed on sustaining the populations of butterflies in prairie-oak ecosystems. The purpose of my study was to examine the role prairie-oak habitats have in structuring butterfly communities in the Willamette Valley. My objectives were to: (1) assess how butterfly community structure and species composition (density, abundance, and species richness) varies along an oak canopy cover gradient in order to understand the role of habitat type in structuring butterfly communities in prairie-oak ecosystems; (2) characterize community composition of nectar resources and environmental variables known to be important for butterfly species. I also investigated temporal and structural relationships between butterfly and flower communities. I found that butterfly abundance and density were greater (p < 0.02) in prairies than in oak savannas or oak woodlands; however, species richness did not differ among habitats (p = 0.54). Ordination of prairie-oak habitats in butterfly species space with a joint plot overlay of environmental variables revealed several strong correlations; butterfly community structure was negatively correlated with litter and oak canopy cover and positively correlated to vegetation cover. The prairie, oak savanna, and oak woodland habitat types differed in nectar species community structure, though this difference was small. Non-native species were some of the most abundant flowers species found in all stands. Butterfly communities were positively related to flower communities. I detected significant seasonal patterns among the habitat types in butterfly and flower communities. Prairies appear to be the most important habitat for native butterfly populations compared to oak savanna and oak woodlands. Flowers were most prevalent in prairies and prairies had the highest percentage of native flower species; the prevalence of non-native flower species was greatest in oak woodlands. My study may represent a short-term community transition as a result of management or it may represent a more permanent community. Further study is needed to understand the effects of different management strategies for habitat restoration and the presence of non-native flower species on butterflies in prairie-oak ecosystems in the Willamette Valley. Close

• 3. [Article] Bird Abundance and Microhabitat Associations with Oak Mistletoe in Willamette Valley Oak Woodlands

  In the last 200 years there have been significant declines in the amount and structural complexity of oak-dominated forests and savannahs in the Pacific Northwest. Restoring oak systems often involves ...

  Citation × Citation Citation Abstract Copy Title: Bird Abundance and Microhabitat Associations with Oak Mistletoe in Willamette Valley Oak Woodlands Author: Pritchard, Kyle R. In the last 200 years there have been significant declines in the amount and structural complexity of oak-dominated forests and savannahs in the Pacific Northwest. Restoring oak systems often involves selectively thinning stands of oaks in order to reduce competition for sunlight. In choosing which trees to cut, land managers often remove trees with obvious signs of disease or infection. One such infection is the parasitic mistletoe Phoradendron villosum, commonly referred to as Oak Mistletoe. However, the consequences of removing mistletoe-laden trees from the woodlands for oak-associated wildlife have not been studied. Mistletoe species play an important role in ecosystems globally, by providing habitat resources for wildlife, but the role of Oak Mistletoe in an oak-dominated ecosystem is almost completely undocumented. In order to investigate relationships between Oak Mistletoe and bird abundance and diversity, I quantified breeding bird use of Oregon White Oaks (Quercus garryana) with mistletoe loads between zero and 112 plants per tree, at five study sites in the Willamette Valley in the spring of 2014. In addition, I quantified six microhabitat features related to mistletoe infection, including branch swellings, dead wood, loose/missing bark, natural cavities, excavated cavities, deep cracks in the bole, and bole coverage by Poison Oak (Toxicodendron diversilobum). My results suggest that 1) structural heterogeneity within the crown of the tree and 2) bird abundance, species richness, and use of trees are positively associated with mistletoe load. In order to investigate the use of Oak Mistletoe fruits as a wildlife food resource, I recruited citizen scientists to record observations of birds feeding on mistletoe fruits in the fall of 2014 and winter of 2015 in western Oregon. In addition, I installed six camera traps in Oregon White Oak trees in order to capture additional observations of birds and other wildlife feeding on Oak Mistletoe fruits. My results suggest that Oak Mistletoe is a fall and winter food resource for Western Bluebirds (Sialia mexicana), American Robins (Turdus migratorius), Cedar Waxwings (Bombycilla cedrorum), Wild Turkeys (Meleagris gallopavo), and Western Grey Squirrels (Sciurus griseus). In this study, Western Bluebirds were observed to feed on mistletoe fruits up to 14 times more frequently than other bird species. By retaining some trees with mistletoe in the crown, land managers may be able to maintain the habitat quality for some wildlife species that use the microhabitat features and fruit resources associated with mistletoe. Title: Bird Abundance and Microhabitat Associations with Oak Mistletoe in Willamette Valley Oak Woodlands Author: Pritchard, Kyle R. In the last 200 years there have been significant declines in the amount and structural complexity of oak-dominated forests and savannahs in the Pacific Northwest. Restoring oak systems often involves selectively thinning stands of oaks in order to reduce competition for sunlight. In choosing which trees to cut, land managers often remove trees with obvious signs of disease or infection. One such infection is the parasitic mistletoe Phoradendron villosum, commonly referred to as Oak Mistletoe. However, the consequences of removing mistletoe-laden trees from the woodlands for oak-associated wildlife have not been studied. Mistletoe species play an important role in ecosystems globally, by providing habitat resources for wildlife, but the role of Oak Mistletoe in an oak-dominated ecosystem is almost completely undocumented. In order to investigate relationships between Oak Mistletoe and bird abundance and diversity, I quantified breeding bird use of Oregon White Oaks (Quercus garryana) with mistletoe loads between zero and 112 plants per tree, at five study sites in the Willamette Valley in the spring of 2014. In addition, I quantified six microhabitat features related to mistletoe infection, including branch swellings, dead wood, loose/missing bark, natural cavities, excavated cavities, deep cracks in the bole, and bole coverage by Poison Oak (Toxicodendron diversilobum). My results suggest that 1) structural heterogeneity within the crown of the tree and 2) bird abundance, species richness, and use of trees are positively associated with mistletoe load. In order to investigate the use of Oak Mistletoe fruits as a wildlife food resource, I recruited citizen scientists to record observations of birds feeding on mistletoe fruits in the fall of 2014 and winter of 2015 in western Oregon. In addition, I installed six camera traps in Oregon White Oak trees in order to capture additional observations of birds and other wildlife feeding on Oak Mistletoe fruits. My results suggest that Oak Mistletoe is a fall and winter food resource for Western Bluebirds (Sialia mexicana), American Robins (Turdus migratorius), Cedar Waxwings (Bombycilla cedrorum), Wild Turkeys (Meleagris gallopavo), and Western Grey Squirrels (Sciurus griseus). In this study, Western Bluebirds were observed to feed on mistletoe fruits up to 14 times more frequently than other bird species. By retaining some trees with mistletoe in the crown, land managers may be able to maintain the habitat quality for some wildlife species that use the microhabitat features and fruit resources associated with mistletoe. Close

• 4. [Article] Monitoring the effects of oak woodland restoration on birds in the Willamette Valley, Oregon

  Pathways Internship Program

  Citation × Citation Citation Abstract Copy Title: Monitoring the effects of oak woodland restoration on birds in the Willamette Valley, Oregon Author: Martinez, Elena Pathways Internship Program Title: Monitoring the effects of oak woodland restoration on birds in the Willamette Valley, Oregon Author: Martinez, Elena Pathways Internship Program Close